The installation of polyurethane-insulated piping is a "hidden project" (concealed work), where attention to detail determines the service life of the pipeline network. Before construction, verify the design drawings against site conditions and strictly inspect all materials: the polyurethane foam must have a density of ≥60 kg/m³ and a closed-cell ratio of ≥90%; the outer protective casing must meet impact resistance standards; and the wall thickness deviation of the steel pipes must not exceed 10%. When excavating trenches, ensure precise control over elevation and slope, and implement a drainage system to prevent water accumulation. During transport and lifting, use soft slings to handle pipes with care, and seal the pipe ends to prevent the entry of debris. During installation, inspect weld bevels, conduct non-destructive testing (NDT) and leak testing, and ensure that welds are positioned away from pipe supports. Field-foaming at joints must match the thickness and protective layer specifications of the original piping, with a particular focus on waterproofing. Install fixed supports and expansion compensators according to the design layout; ensure that air release valves are placed at high points and drain valves at low points. Waterproofing is of critical importance-joints and support piers must be sealed tightly. Backfilling must be performed using sand, which must be compacted; the use of debris-laden soil for backfilling is strictly prohibited. For the hydrostatic pressure test, maintain a pressure equal to 1.5 times the design pressure for one hour; the pressure drop must not exceed 0.05 MPa, and there must be no signs of leakage. Following the pressure test, flush the pipelines in the prescribed sequence. Do not perform insulation work during rain or snow, and ensure comprehensive protection of the installed components and strict adherence to safety protocols throughout the process. Each stage of construction requires on-site supervision and thorough documentation to guarantee the long-term, safe, and reliable operation of the heating pipeline network.